Many traditional Public Switched Telephone Networks (PSTN) utilize the Signaling System 7 (SS7) messaging protocol stack to establish and terminate telephone calls, as well as provide enhanced telephone functionality such as number translation and short message services (SMS). The Message Transfer Part (MTP) is a component of the SS7 protocol stack, and covers several functions including network communication, data transmission, and message routing to higher levels of the SS7 protocol stack.
The MTP is divided into three levels, each corresponding to a different type of functionality. MTP Level 1 is the Signaling Data Link Functional Level (Data Link Level), MTP Level 2 is the Signaling Link Functional Level (Link Level), and MTP Level 3 is the Signaling Network Functional Level (Network Level). Other components of the SS7 protocol stack are considered MTP Users. MTP Users include the Signaling Connection Control Part (SCCP), the Integrated Services Digital Network (ISDN), the ISDN User Part (ISUP), or the Telephone User Part (TUP).
MTP Level 3 (also called MTP3) provides routing functionality to transport signaling messages through the SS7 network to the requested endpoint. MTP3 is also responsible for network management; when the availability of MTP Level 2 data links changes, MTP3 establishes alternative links as required and propagates information about route availability through the network. Each network element in the SS7 network has a unique identifier called a point code. Message routing is performed based on the point code, and each end of an MTP3 link must bear a unique point code.
MTP3 is limited to use in the SS7 network. The recent and dramatic proliferation of Internet Protocol (IP) networks across all forms of communication has led service providers to take advantage of the availability, flexibility and scalability of the IP networks to offer IP-based telephony services. Therefore, integration of the protocols used by the pre-existing SS7 telephony networks and the newer IP networks to allow communication between the two types of networks is a crucial element to providing robust and easily accessible telephony services.
In response to the challenge of integrating these types of networks, a set of protocols called SIGTRAN was developed based on the traditional SS7 protocols but extending the SS7 functionality to IP-based transport and communication mechanisms. One of the SIGTRAN protocols, MTP Level 3 User Adaptation (M3UA), enables the MTP3 User Parts (e.g., ISUP, SCCP and TUP) of the SS7 protocols to run over IP-based networks instead of traditional telephony networks (e.g., PSTN).
Links in the MTP3 protocol are traditionally defined by the two distinct point codes at each end of the link. The nature of the M3UA protocol, however, requires the two ends to bear the same point code. Thus, the traditional definition of links using point codes under the MTP3 protocol is not applicable to M3UA. In addition, the definition of the M3UA protocol is focused on having a single M3UA interface between the MTP3 and its user(s).
High availability, load balancing, and scalability are essential requirements of modern communication networks. Conventional systems are unable to meet these requirements. A need therefore exists for improved methods and apparatuses for establishing M3UA linksets and routes.